Forgeries of identification cards, drivers' licenses and other documents that confer authorization and/or security clearance continues to be a major concern. The availability of sophisticated technology enables forgers to create counterfeit copies of many different kinds of personal and professional materials more easily than ever before. No system currently is available to insure that a picture or more broadly, one type of information, and the corresponding information in another form in an underlying document, such as an identification card, belong together.
Since their inception, bar codes have been used to encode all sorts of information. Bar codes contain information in the bars and spaces that is interpreted by electronic devices, referred to herein as bar code reading devices. A bar code reading device, including, for example, a scanner, wand, optical scanner or verifier, reads the bars and spaces by measuring their widths and decoding the dimensions according to the rules of the particular bar code, known as its “symbology.” A bar code symbology is a set of encoding algorithms that essentially provide the grammar for the production of the bar code pattern. As in written languages, bar code symbologies have rules of grammar that dictate how the pattern of bars and spaces are formed for any particular code data. Examples of recognized bar code symbologies include UCC/EAN 128, Codabar, Code 128, Code 39, Code 93, UPC-A, UPC-E, JAN-13, ITF, ISSN, ITF and ISBN. Typically, a bar code reading device determines the differences between the thickness of the bars and the thickness of the spaces by counting light and dark pulses of light as the reading device is drawn across the bars.
Among the most common bar code symbologies in the U.S. and Canada is the Universal Product Code (UPC-A). As shown in FIG. 1, a UPC-A bar code symbol's pattern of bars and spaces is a unit bar 10. Unit bar 10 is a narrow bar having a predetermined width for a bar code symbol at a given magnification. The dimensions of the bars and spaces in the symbol are exact multiples of the unit bar. Thus, double bar 12 in the symbol is twice as wide as unit bar 10, while triple bar 14 is three times as wide and quadruple bar 16 is four times as wide.
Each bar code symbol begins and ends with start and stop characters, referred to herein as frame bars. Frame bars are unique to the symbology involved and instruct a bar code reading device what symbology to expect when reading the symbol. The frame bars in the symbol shown in FIG. 1 are composed of unit bars 10.
For each bar code symbology, there are published specifications to provide instructions for those producing bar codes. ANSI standards are widely regarded as the accepted standard for each symbology. Bar code systems are issued with the instructions so that all participants will conform to the published standards. In order to measure how closely a bar code symbol meets these standards, electronic verifiers can be used.
Whether a bar code symbol can be read depends, in part, on the ability of a bar code reading device to measure the relative widths of the bars and spaces of a bar code. The ability of a bar code reader to discern the relative widths of the bars and spaces depends upon the contrast between the bars and spaces in a bar code. Most symbologies require at least a 50% contrast between the darken portion (i.e., the bars) and the light portion (i.e., the spaces). Without a contrast of at least 50% between the bars and spaces for many symbologies, a bar code may be unreadable.
Many forms of identification documents and the like comprise bar codes. However, using sophisticated graphic computer software, forgers can remove an image from an identification card, and, replace the image with one that does not represent the true owner of the card.